Ice water is homogeneous or heterogeneous. Is it is a pure or impure substance ?

A ball is thrown up with a velocity of $19.6 \mathrm{m}/\mathrm{s}$. The time taken by the ball to reach at maximum height is calculated as,
At maximum height, the final velocity of the ball,

$\mathrm{v}=0$

From the equation of vertical motion

${\mathrm{v}}^2={\mathrm{u}}^2-2\mathrm{gh}$  [$\because g=9.8 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$]

$$\begin{gathered} 0=(19.6{)}^2-2\times 9.8\times h \\ \Rightarrow h=19.6 \mathrm{m} \end{gathered}$$

From the equation of upward motion

$h=ut-\frac{1}{2}g{t}^2$

$$\begin{gathered} 19.6=19.6t=\frac{1}{2}\times 9.8t^2 \\ 4=4t-t^2 \\ (t-2{)}^2=0 \\ t=2s \end{gathered}$$

Calculate the time taken by the ball to reach at maximum height by the alternate method.

Calculate the number of moles present in

$\left(\mathrm{i}\right)$ $60 \mathrm{ml}$ of calcium
$\left(\mathrm{ii}\right)$ $3.011\times {10}^{23}$ number of oxygen atoms.

[Given that $\mathrm{Ca}=40 \mathrm{u}$; avogardo number, ${\mathrm{N}}_{\mathrm{A}}=6.022\times {10}^{23}$ per mole]

A boy wants to separate a mixture of alcohol (boiling point $78°\mathrm{C}$) and water (boiling point $100°\mathrm{C}$), he used fractional distillation process to separate both the liquids. The diagrammatic representation of the process is given below

Analyse and compile the above information to describe the whole process of separation of two miscible liquids.

What is the direction of acceleration of the ball during the upward motion ?